GNU Info

(gcc-300.info)Insn Attributes

---

Next: Conditional Execution Prev: Peephole Definitions Up: Machine Desc

---

Enter node , (file) or (file)node

Instruction Attributes
======================

   In addition to describing the instruction supported by the target
machine, the `md' file also defines a group of "attributes" and a set of
values for each.  Every generated insn is assigned a value for each
attribute.  One possible attribute would be the effect that the insn
has on the machine's condition code.  This attribute can then be used
by `NOTICE_UPDATE_CC' to track the condition codes.

Defining Attributes

Specifying attributes and their values.

Expressions

Valid expressions for attribute values.

Tagging Insns

Assigning attribute values to insns.

Attr Example

An example of assigning attributes.

Insn Lengths

Computing the length of insns.

Constant Attributes

Defining attributes that are constant.

Delay Slots

Defining delay slots required for a machine.

Function Units

Specifying information for insn scheduling.